Casement and picture windows present a combination of problems, including aesthetic appeal, ease of installation, economy in manufacture, thermal insulation and weatherproofing.
Windows are available which satisfy one or some of these requirements, but generally speaking it has not been possible to achieve a satisfactory solution to all of these requirements in any one window.
Various different materials have been used in the past for such windows, with mixed results. Extrusion of a window frame in plastics material typically vinyl plastics materal offers numerous advantages from the viewpoint of economy, and weather resistance. However, in the past vinyl extruded windows of this type have generally speaking been either excessively complex in design or else have provided an inadequate seal either between the building fabric and the window frame, or between the frame and the glazing.
In addition, the method of installation of this type of window in the building fabric has not been satisfactory.
It is advantageous if the window design of a picture window is of two part construction consisting of a window border and flashing, of rectangular construction, designed to be fastened in position in the window opening, and a window housing attached to the window border.
A casement window will advantageously be of three-part construction, including the above components, and a glazing frame hinged on the housing.